topic badge

4.035 Estimating area

Lesson

Estimating area

Sometimes we may only want an idea of the area of something, without needing an exact measurement. In such a case there are some techniques we can use to estimate area:

  • Using a mental image of a common objects of size $1$1 mm2, $1$1 cm2, $1$1 m2 and/or $1$1 km2, try to picture how many it would take to cover the object.
  • For shapes that are rectangular (or close to rectangular), we can estimate the length and width of the object and then multiply: $\text{Area}=\text{length}\times\text{width}$Area=length×width.
  • If a picture of the item is available, you could draw a scale grid over it and estimate by counting the number of squares needed to cover the item.

 

Practice questions

Question 1

Estimate the area of the artwork above the sofa if the sofa is $1.9$1.9m in length.

  1. $1.7$1.7 m2

    A

    $0.01$0.01 m2

    B

    $5$5 m2

    C

    $0.5$0.5 m2

    D

Question 2

Estimate the area of the curved shape below if each square on the grid has an area of $3$3 mm2.

  1. $111$111 mm2

    A

    $72$72 mm2

    B

    $26$26 mm2

    C

    $48$48 mm2

    D

Question 3

Which of these objects do you think would have an area of about $1$1m2?

  1. goal area on a football field

    A

    lid of a shoe box

    B

    coffee table

    C

    baking tray

    D

 

Outcomes

ACMEM021

use metric units of area, their abbreviations, conversions between them, and appropriate choices of units

ACMEM022

estimate the areas of different shapes

What is Mathspace

About Mathspace